The present invention generally relates to writing instruments, and more particularly to a writing instrument having a seat that automatically adjusts to accept refills of different lengths.
It is commonplace for pen manufacturers to make refill cartridges that vary in diameter and length from those of their competitors. Manufacturers each typically make their pen housings with an elongated internal chamber, which encloses the refill cartridge, of a unique length to match the length of its own brand refills. Accordingly, the refill seat against which the non-writing end of the refill abuts is at a fixed position with respect to the pen housing, thereby setting the length of the refill chamber. This practice often precludes consumers from using refills from one manufacturer in other manufacturer""s pens because the writing point of the refill cartridge (which delivers the ink) will not protrude from the end of the pen housing by the proper amount for writing. Thus, the point may extend either too little or too far in relation to the end of the pen housing. This situation may also interfere with the proper fitting of caps or other end closures that are typically used in non-retractable pen designs, or with the proper operation of retractable pen mechanisms.
The problems created by varying length refills may also plague a single manfacturer""s line of writing instruments. Such may be the case when the consumer attempts to change the type of refill that is used in a particular pen. For example, ballpoint refills often vary in length from rollerball refills even from the same manfacturer. Therefore, different type refills cannot readily be used interchangeably with a particular pen design. This can be frustrating to consumers, particularly those who purchase reuseable quality pens which typically command a higher market price than disposable models. Thus, the consumer has little flexibility and is locked into the type of refill that can be used at the time the pen is purchased. Furthermore, the availability of refills for particular models of pens is often problematic for the consumer, especially if the model has been discontinued.
To overcome the aforementioned problems, a number of approaches have been attempted in the past with limited success to accommodate varying length refills. For instance, one common approach exemplified by U.S. Pat. No. 3,039,437 has been to provide refill cartridges with different length plugs that are intended to be manually inserted into the non-writing end of the refill by the consumer, thereby functionally altering the length of the replacement or refill cartridge. Through a trial and error process, the consumer must try to select the plug that will yield the proper length when the refill is installed in the particular pen""s refill chamber (assuming that the proper plug has even been provided with the refill kit in the first instance). This potential solution is not only inconvenient for the consumer, but also increases refill cartridge costs because the manufacturer must make and supply an assortment of plugs with each refill kit.
Another approach directed towards varying the operative length of the refill itself is to provide a plastic refill that must be manually cut to proper length by the consumer as disclosed in U.S. Pat. No. 5,615,964. This approach, however, is similarly inconvenient, may result in ink leakage, and is not adaptable to many of today""s metal refills such as those found in higher end pens. Yet another variation disclosed in U.S. Pat. No. 2,914,027 consists of an inner refill cartridge having a helically grooved tube with a concentric outer sleeve member which moves up and down on the tube to vary the length of the refill. After the consumer determines the proper length of the refill, the length of the refill is manually locked into place by a clamping collar which affixes the inner tube to the outer sleeve member. German patent DE 3637875 utilizes a collect chuck mechanism that grabs the refill and is adjustable to vary the position of the refill within the writing instrument with respect to the writing end of the barrel. This design also requires manual manipulation of the collet mechanism to adjust the position of the refill in the pen housing so that the refill point protrudes the proper distance for writing. The collet chuck design is also somewhat mechanically complex and not inexpensive to produce.
In sum, the design approaches of the past have inconvenienced consumers by requiring various types of manual adjustments to be made and with which the consumer would rather not be bothered. Accordingly, there is a need for a refill seat that is not only simple in design and economical to produce, but also that automatically adjusts the refill chamber length to accept refills of different lengths.
The invention is generally directed to a refill seat for a writing instrument having an internal chamber. More particularly, the invention relates to a refill seat mechanism that automatically adjusts the length of the chamber within a writing instrument to accept refills of different lengths. Accordingly, consumers are not required to manually manipulate the writing instrument or the refill to change the chamber length. The chamber length automatically adjusts to the proper length based on the length of the refill that is inserted into the writing instrument. Briefly stated, consumers uncouple the writing instrument housing, insert the refill of choice, and recouple the writing instrument housing. The refill now automatically assumes its proper position within the writing instrument for writing (i.e., writing end of refill which delivers ink to the writing surface is projected by a correct amount beyond the front end of the instrument), and is ready to be used.
The automatically-adjusting refill seat mechanism comprises a first element having a seating surface and a second element having a seating surface. The seating surfaces, either alone or in combination, form a stop to prevent the refill from sinking into the housing chamber too far such that the writing end of the refill is not projected beyond the front of the writing instrument for writing. The second element is moveable in position with respect to and operably slidably engaged with the first element. The second element may be moveable in a continuum of positions with respect to the first element. In one embodiment, the second element is moveable from a first position to a second position with respect to the first element. The movement of the second element creates different chamber lengths which are associated with the first and second positions of the second element. Both the first and second elements are configured and adapted to fit in a writing instrument. Accordingly, the size of the first and second elements may be determined based upon the size of the writing instrument in which they will be used, but adapt to variously sized refills to be contained in the housing.
Different length refill cartridges having variously sized and configured seating ends (i.e., the end of the refill opposite the writing end) may be used with the present invention such that when inserted in a writing instrument, the refill is in the proper position for writing. Thus, the type of refill cartridge provided and its seating end design (i.e., size and configuration) will determine whether the first and/or second elements become engaged by the refill cartridge when inserted in a writing instrument having the refill seat mechanism of the present invention. Preferably, therefore, the seating surfaces of the first and second elements are cooperatively sized and configured with the length and seating end type of the different refill cartridges that may be used. For example, a first type of refill cartridge may engage the first element without engaging the second element. In another example, a second type of refill cartridge may engage the second element without engaging the first element. And in another example, a third type of refill cartridge may engage both the first and second elements. In the foregoing examples, it is apparent that the second element may either be automatically moved or not moved (as a matter of design choice) with respect to the first element to provide the correct chamber length within the writing instrument for centering the particular refill cartridge used in the proper position for writing. Thus, refills of different lengths are usable in the same writing instrument having a refill seat mechanism in accordance with the principles of the present invention. A biasing member may be interposed between the first and second elements to releasably hold the second element in the first position when not engaged by a refill; however, a biasing member is not necessary.
In one embodiment, the first element may be a rod and the second element may be a sleeve that is slidable on the rod. The biasing member may be a helical spring suitable to bias the first and second elements apart, yet permit movement of the first and second elements towards each other.
In accordance with another embodiment, a separate refill seat may be provided that is moveable from a first position to a second position with respect to the first element. The refill seat may be axially slidably engaged with the first element. In one embodiment, the movement of the seat from the first to second position creates different chamber lengths, which in an embodiment may be two chamber lengths. In another embodiment, the movement of the seat may create three different chamber lengths. The refill seat may have a head and a stem attached thereto. In another embodiment, the refill seat and the first element have mating angled surfaces to create produce the first and second positions of the seat. However, angled surfaces are not necessarily required and the first and second positions of the seat may be achieved in other ways in various embodiments.
A method is also described for using refills of different lengths in a writing instrument provided with an automatically-adjusting refill seat mechanism. The writing instrument has a housing made up of a lower portion coupled to an upper portion defining an elongated internal chamber therein for centering a refill. To use the refill seat mechanism, the lower and upper housing portions are first uncoupled and a refill is inserted into the internal chamber. The upper and lower housing portions are then recoupled, whereupon the refill seat mechanism automatically adjusts the chamber length to match and properly to fit the length of the refill selected, without requiring any manual adjustments to the length of the chamber.